1. Field of the Invention
The present invention relates to furnaces, and more particularly to a fluid cooled dump grate used in a fuel cell, the fuel cell operable to produce heated gases from burning fuel for use as a drying medium.
In certain industrial applications, it is preferable to use dump grates for supporting burning fuel and then dumping spent fuel into an ash pit. However, because of great heat generated during such burning processes, it is necessary that the dump grate or grates be cooled. Cooling can be effectuated by either introducing air or fluid coolant to contact the dump grates. While introducing air serves to cool dump grates somewhat, it has been found that fluid flowing through coolant tubes disposed in the dump grate is desirable.
Fluid coolant tubes embedded or otherwise used within a grate plate may effectively transfer heat from the grate plate material to the fluid. However, it is often preferable to have grate plates which may be tilted in order to dump spent fuel material into an ash pit. A problem arises in constructing a rotatable dump grate plate which will permit coolant fluid to be continuously introduced and discharged through coolant fluid tubes disposed within the grate plate during a dumping operation. Furthermore, it is also desirable to provide a means so that the amount of air which may be channeled through grate plate openings may be varied.
2. Description of the Prior Art
Rotatable dump grates are known. A typical example is exemplified by U.S. Pat. No. 1,172,002. This patent describes a grate which permits water to be introduced and discharged through a conduit extending around the margin of the grate. Ports arranged in a trunnion of the grate enable water to be introduced into the conduit and discharged therefrom. However, the ports are so arranged to permit introduction and discharge of water only when the grate is in a horizontal position. When the grate is turned or rocked, the ports are turned out of communication with the fluid introduction and discharge means so that coolant fluid may not be continuously circulated through the conduit. Thus, it is readily apparent that the construction described in this patent does not provide for continuous cooling of a dump grate.
A fuel cell is disclosed in U.S. Pat. No. 3,330,259 and includes a hearth composed of water cooled grates around which rises a water cooled upright section so that air can be directed through the hearth and the upright grate section to effect an adequate supply of air to the hearth zone while maintaining the temperature of the zone below a predetermined value. However, it is to be noted that the hearth is not constructed so that it can dump spent fuel material into an ash pit.